This invention relates to a device for preventing curling of a material derived from the thermal developing and/or transfer step in a thermal developing machine.
Concerning the diffusion transfer type thermal developing in which a diffusible dye is released by thermal developing and the dye is transferred onto an image-receiving element to obtain a color image by separation of the recorded image and the dye, there have already been a large number of technical disclosures about light-sensitive elements, image-receiving elements, thermal developing methods and devices therefor. A typical example comprises passing an image-receiving element and a thermal developing light-sensitive element superposed on one another with the dye fixing layer surface and the light-sensitive layer surface faced to each other between a pair of rollers capable of effecting uniform heating and pressurization.
Next, both of the superposed elements are heated uniformly to effect thermal developing and have the dye which is released from the thermal developing light-sensitive element by thermal developing, transferred onto the dye fixing layer, and then the above two sheets can be peeled off to form an image on the image-receiving element.
In this method, when the superposed light-sensitive element and the image-receiving element are subjected to thermal developing transfer, the superposed state is required to be maintained for a predetermined period of time, and therefore it has been considered to pass the light-sensitive element and the image-receiving element linearly between a pair of flat belts. Also, it is considered to pass them between a drum and a belt opposed thereto.
On the other hand, a thermally developing light-sensitive material is used according to the present invention which is different from the type requiring superposing the light-sensitive element and the image-receiving element on one another as described above. In particular an integral type thermal developing light-sensitive material (thermal developing light-sensitive material having at least a light-sensitive layer, a white reflective layer and an image-receiving layer on the same support) may be also employed. As to such integral type thermal developing light-sensitive materials, they are shown in, for example, Japanese Unexamined Patent Publication No. 80,148/1986; and Japanese patent application No. 254,257/1986 "(Title: Mono-sheet type thermal developing light-sensitive material, Applicant: Konishiroku Photo Industry K. K., Filing date: Oct. 25, 1986. Japanese patent application No. 254,257/1986 was published as Japanese Unexamined Patent Publication No. 108,337/1988 (published May 13, 1988).
The basic layer constitution of the integral type thermal developing light-sensitive material has a subbing layer, a light-sensitive layer (having 1 or 2 or more layers, and may have an intermediate layer when having two or more layers), a white reflective layer, an image-receiving layer and a protective layer in this order mentioned from the support.
Also in the case of such integral type thermal developing light-sensitive material, except for requiring no superposing mechanism, thermal developing transfer can be effected by the same device as described above to form an image on the image-receiving layer.
Anyway, for thermal developing transfer, it is requested to maintain both elements or the integral type thermal developing light-sensitive material at a certain high temperature state for a predetermined time. The system considered for such heating is generally the system to press the heat block against at least one belt in the belt-belt type of the former, while it is the system of using a heated drum as the drum in the drum-belt type of the latter.
The drum-belt type as mentioned above is better in thermal developing transfer processability as compared with the belt-belt type.
More specifically, in this type, the respective elements are conveyed under a superposed state between the drum and the belt. Therefore, tension of the belt acts uniformly on the whole opposed surface with the belt, whereby uniform pressing is possible to give uniform adhesion between the both elements and enhance easily the adhesive force in proportion to the tension, which is particularly suitable in the case of thin element thickness. Also, since the respective elements lie along the curvature of the drum surface, they are excellent in running performance and will not go apart from the drum. For such reasons, generation of transfer irregularity can be prevented.
Also by using a heated drum as the drum, in the conveying process, the material can be directly heated, whereby heating characteristic can be also excellent.
However, according to this system, since the conveying passage is shaped in an arc and also heat is given in the conveying process, the material is delivered from the thermal developing transfer step under a state substantially along its arc, and the curling cannot be remedied even after elapse of time.
Also, even in the case of passing a material on a plane as in the belt-belt type, curling will occur when the elongation degree by heating between the light-sensitive sheet and the image-receiving sheet is different.
If there is such curling, when piling on a stocker with both sheets separated from each other, piling difficulties may be brought about, or commercial product value may be significantly lowered.